1. Technical Field
The present invention relates to a wireless broadband (WiBro) station capable of supporting Quality of Service (QoS) and a method for servicing the QoS in a WiBro network.
2. Related Art
Wireless Broadband (WiBro) is a super-speed portable Internet service that mainly targets data communication, as well as Quality of Service (QoS)-based high-quality multimedia data such as voice, image and so on, using a frequency of 2.3 GHz. It allows the data communication and the use of the Internet even during high-speed movement, and it is based on the standard IEEE 802.16e.
One feature of the WiBro service is to provide a differentiated service, i.e. a QoS service, according to the type of service that a subscriber uses. Therefore, the WiBro network and system are designed so as to be able to support the QoS at a Media Access Control (MAC) layer on the basis of the standard IEEE 802.16e. In general, among QoS services, the lowest level of service is a Best Effort (BE) service, which equally treats all traffic independent of the application or the state of a station.
A method for distinguishing packets by applications in the network layer includes Internet Protocol Type Of Service (IPTOS), Differentiated Services Code Point (DSCP), and so on. IPTOS is used by defining an 8-bit service field in an Internet Protocol version 4 (IPv4) packet, wherein the service field includes a 4-bit Type Of Service (TOS) field. DSCP or DiffServ is a new model in which traffic is treated by intermediate systems with a relative priority based on the TOS field. DiffServ architecture defines a DiffServ (DS) field, which supersedes the ToS field in IPv4.
For the QoS service, procedures for QoS negotiation, acceptance control, wireless section band request and allocation between the stations, the relay and the core network should be carried out. QoS negotiation refers to negotiation between QoS that the station requests (Active QoS), QoS that the base station can accept (Admitted QoS), and QoS that is registered with an authentication server according to each subscriber (Provisioned QoS). Acceptance control is carried out through Access Point (AP) flow, AP handover, Packet Access Router (PAR) flow, and PAR handover. The wireless section band request and allocation broadcast information on a frame configuration using a DownLink-Mobile Application Part (DL-MAP) and UpLink-MAP (UL-MAP) according to each frame. The station transmits data in a corresponding section.
Measurement of QoS occurs at the base station and PAR according to each registered service. When a traffic packet is received, a determination is made as to whether or not the packet is within a traffic descriptor negotiated based on a time and a data rate. If the packet is not within the negotiated traffic descriptor, the base station and PAR cannot process the traffic with respect to the packet.
In order for the base station to identify a UL section user, information on a mobile station-specific band request is required. The mobile station requests a UL band with a band request message or a data grant message using a piggyback function. In a contention-based band request, the mobile station initially uses a Code Division Multiple Access (CDMA) code in order to make a request to the base station to transmit the data. The base station allocates a band corresponding to the band request message to the received band request CDMA code. The mobile station transmits the band request message to the base station with the allocated band, and presents the band request message with the requested UL band. The base station reflects information on the request band in UL scheduling. The contention-based band request is provided to each user in a unicast mode, and thus is not applied to a multicast or broadcast service.
In a polling-based band request, the base station allocates the UL section band to the mobile station, thereby collecting information. The mobile station records a data rate to be transmitted on the band request message, and transmits the recorded band request message to the base station. The base station performs scheduling on the basis of the collected information, and allocates a user-specific band to the UL section according to results of the scheduling.
When data to be transmitted exists in a buffer at the mobile station's request for a band, a piggyback band request is used to request the band by addition to transmitted traffic, and transmits a data sub-header to the base station together with information on an additional band request. The base station recognizes a band adding an additional band to a band that is previously requested but not allocated as band request information which the mobile station requests, and applies the recognition to the UL scheduling.
As observed above, the 802.16e standard for the WiBro service uses a method of classifying the packets with a classifier allocated to Layer 2 in order to provide QoS. Thus, in order to give a QoS level according to the feature of the packet, all application packets should be parsed in Layer 2, and thereby the feature of each packet should be analyzed. Consequently, the parsing in Layer 2 increases the burden imposed on a modem.